[Editor’s note: This post is excerpted from next week’s forthcoming NORML weekly media advisory. To have NORML’s news alerts and legislative advisories delivered straight to your in-box, sign up here.]

Commercially available baby soaps and other wash products that are commonly used with newborns may yield false positive results for THC in immunoassay drug screens, according to a just published study in the journal Clinical Biochemistry.

Investigators at the University of North Carolina, Department of Pathology and Laboratory Medicine, assessed the impact of various baby wash products on drug-free urine samples after a number of false positive cannabinoid screening results were suspected at their hospital.

Researchers reported: “Mixtures of drug-free urine with various commercial products and materials that commonly contact newborns in our nursery were prepared and tested using the immunoassay screening methods in our laboratory. … Addition of Head-to-Toe Baby Wash to drug-free urine produced a dose dependent measureable response in the THC immunoassay. Addition of other commercially available baby soaps gave similar results, and subsequent testing identified specific chemical surfactants that reacted with the THC immunoassay.”

They concluded: “We have identified commonly used soap and wash products used for newborn and infant care as potential causes of false positive THC screening results. Such results in this population can lead to involvement by social services or false child abuse allegations. Given these consequences, it is important for laboratories and providers to be aware of this potential source for false positive screening results and to consider confirmation before initiating interventions.”

Read the abstract of the study, “Unexpected interference of baby wash products with a cannabinoid (THC) immunoassay,” here.